1. Field of the Invention
The present invention relates to an optical disk apparatus capable of reproducing or both recording and reproducing of signals which are greatly different in the frequency band from each other, such as an NTSC signal and a high definition television signal.
2. Description of the Prior Art
Optical disk apparatuses capable of reproducing or both recording and reproducing one of an NTSC signal and a high definition television signal have been distributed and reported hitherto. However, all of them are of the analog recording type and are optimally designed for individual signal bands, so that they are not compatible with each other. In the case of digital recording, the quantity of information is by far greater than that in the analog recording. Thus, it was not realistic to employ digital recording in the aspects of reducing the recording and reproducing time and extending the transfer rate. In other words, there was no optical disk apparatus capable of reproducing or both recording and reproducing both the NTSC signal and the high definition television signal. Even if the recording signals are of the same type, there was no optical disk apparatus capable of reproducing or both recording and reproducing in both a low-definition, long-playing mode at a high compression rate and a high-definition, short-playing mode at a low compression rate.